Sebastian Zapeta-Calil repeatedly told detectives he had no memory of an attack that killed a woman who was set ablaze on the New York City subway train he was riding the morning of December 22, according to court documents, writes CNN.

Then, investigators played surveillance video that allegedly caught him igniting the flames.

"Oh, damn, that"s me", Zapeta-Calil said during questioning with police that was transcribed and translated, according to the documents. "I am very sorry. I didn’t mean to. But I really don’t know. I don’t know what happened, but I’m very sorry for that woman", Zapeta-Calil told police, according to the court documents.

Zapeta-Calil, 33, an undocumented migrant from Guatemala, pleaded not guilty to murder charges Tuesday in the death of Debrina Kawam, 57, and was ordered held without bail. He was previously indicted on charges of first- and second-degree murder and arson in the killing. CNN has reached out to his lawyer for comment.

Police say Zapeta-Calil calmly walked up to Kawam as she was sleeping on an F train approaching the Coney Island–Stillwell Avenue subway station in Brooklyn and used a lighter to ignite her clothes and the blanket that was wrapped around her. Kawam, who authorities say resided in New Jersey after a stint in New York’s shelter system, died by homicide caused by thermal injuries and smoke inhalation, according to a complaint filed in Brooklyn Criminal Court. The attack has stoked fears among New Yorkers about safety on subways and in the city at large, after several high-profile, violent incidents in recent years.

“It is difficult to fathom what could lead someone to commit the atrocious and horrific murder with which this defendant is charged,” Brooklyn District Attorney Eric Gonzalez said Tuesday in a statement. “My office swiftly obtained an indictment, and we are determined to exact the most severe punishment for this heinous and inhumane act. Ms. Kawam and her loved ones deserve a measure of justice and New Yorkers deserve to feel safe in the subways”.

After Zapeta-Calil was indicted, Gonzalez noted the defendant faces the possibility of life in prison without parole if convicted of first-degree murder. During an initial court appearance in December, Zapeta-Calil claimed to have no knowledge of the incident, noting his alcohol consumption.